Quit Compressor, or do this before you try to use Compressor. If I’m working from FCP I usually quit that, too, but I think that might be unneccissary.
Launch Terminal (Application>Utilities>Terminal) and type this:
sudo /Library/StartupItems/Qmaster/Qmaster
(I saved in in a text file so I can cut and paste it when I need it, which is always).
Terminal will then ask for your system password, enter the password and hit enter. (BTW, When you put in your password you wont see it on the screen, but it is working.)
Quit terminal and open Compressor, or go back to FCP, and Voila!
If you reboot the computer you have to do this over again, it doesn’t stay “fixed”.
I can’t take the credit for this, I found it in the Apple Compressor discussion.
DWR